Most of the Jersey Boys cast are veterans of the stage play, but there are some flat performances.

A MUSICAL is often only as good as its songs.

By this rationale, Jersey Boys should be outstanding - Sherry, Walk Like A Man, Big Girls Don't Cry, Can't Take My Eyes Off You, and December, 1963 (Oh What A Night) are all classic tracks.

Unfortunately the rest of the film can't quite live up to the quality of these hits. Jersey Boys is, at best, a great story poorly told, and at worst, a mildly disappointing disservice to the legacy of Frankie Valli and The Four Seasons.

For those unfamiliar with the stage musical that inspired it or the back story beyond the Rock 'n' Roll Hall Of Fame inductees, Jersey Boys tells the story of how Francesco Castelluccio aka Frankie Valli (Lloyd Young), Tommy DeVito (Piazza), and Nick Massi (Lomenda) hooked up with songwriter Bob Guadio (Bergen) and became The Four Seasons.

It's a typical rock 'n' roll story - the troubled upbringings, the initial rejections, the fortuitous break with the "wild new sound", the dizzying highs of hit records and parties and girls, the stresses of life on the road, the broken relationships, the in-fighting, the ultimate come-down, the break-up and the inevitable reunion.

It reads like a list of music biopic clichés or the plot of a film parodying the genre (such as Spinal Tap, A Mighty Wind, or Walk Hard: The Dewey Cox Story), but it's a cliché for a reason because it's a common trajectory for bands.

In this case, a lot of these aspects have been re-arranged to better suit the familiar arc, but really that's neither here nor there - "based on a true story" is always only ever loosely "based", so don't take this movie as Four Seasons gospel.

What matters is that in laying out this familiar arc, director Eastwood and writers Marshall Brickman and Rick Elice have laid things out in a weird and frustrating manner.

After rolling along pleasantly and slightly undramatically for much of the film (during which apparently eight years elapses), the beginning of the downward spiral is sprung on the audience, only for the film to then rewind two years and give us all the drama that's been missing.

With much of the dramatic tension and heightened inter-relationships in the band squeezed into an enthralling half an hour, the rest of the film - before and after - feels flat. Plot threads arise seemingly out of nowhere and then disappear and the story's arrangement seems almost random.

The movie really comes to life during the songs, which are worked in unobtrusively via live gigs, TV performances, rehearsals or recording sessions. Jersey Boys is magical when the band plays - Eastwood stages the songs nicely, the actors impress with their vocal skills (yep, they're really singing), and you want to applaud each track when it finishes.

The songs are the saving grace of the film and helps you ignore the dull patches, the occasional flat performances, the strange layout of the plot, the disturbingly bad make-up used to make the band members look older towards the end, and the annoying technique of characters narrating straight to camera. This last matter is of particular frustration because it's utterly redundant (the characters don't tell us anything we don't already know or immediately find out) and it breaks the flow of the film.

Musically, the cast does well (most are veterans of the stage play), but there are some flat performances. Lloyd Young struggles in the really dramatic scenes, particularly one where Valli confronts his wayward daughter (another out-of-nowhere plot thread), Lomenda is only just passable, while Walken is okay but seems to have wandered in from a different movie.

It's not all bad. The early scenes, which have a hint of Goodfellas about them, are good, as are the occasional comedic touches, and that brief half an hour where the drama kicks in is excellent. Piazza and Bergen are particularly good, as is Joey Russo as Joe Pesci (yes, that Joe Pesci).

But ultimately this is a two-star movie that gets an extra star for its excellent songs.